T<sup>#</sup>2-Li<sub>0.69</sub>CoO<sub>2</sub>: A Durable, High-Capacity, High-Rate Cathode Material for Lithium-Ion Batteries.

Zuo, Yuxuan; Liu, Jiahui; Wang, Hangchao; Zou, Ying; Luo, Tie; Zhang, Kun; Yang, Yali; Gao, Chuan et al. · Adv Mater · 2025

basic_science · Level V

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Abstract

Efficient utilization of resources is crucial for the sustainable development of the lithium-ion battery industry. Although the traditional R <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics><mover><mn>3</mn> <mo>¯</mo></mover> <annotation>$\bar{3}$</annotation></semantics> </math> m space group LiCoO<sub>2</sub> can provide a current advanced discharge capacity of 215-220 mAh g⁻¹ at an upper cut-off voltage of 4.6 V (relative to Li⁺/Li), it still falls far short of its theoretical specific capacity of 273 mAh g⁻¹, and exhibits structural instability and labile oxygen loss, leading to rapid capacity degradation. T<sup>#</sup>2-Li<sub>0.69</sub>CoO<sub>2</sub> is synthesized with Cmca space group and Li─O tetrahedral coordination. Owing to the unique Li─O tetrahedral coordination structure and the dominant cobalt oxidation under high voltage, T<sup>#</sup>2-Li<sub>0.69</sub>CoO<sub>2</sub> delivers an ultra-high specific capacity of 258 mAh g<sup>-1</sup>, close to the theoretical capacity, in liquid electrolyte batteries and 253 mAh g<sup>-1</sup> in solid state batteries, overcoming the structural instability of layered oxide cathodes during charging and discharging processes. This study broadens the possibilities of creating high energy-density cathodes for next-generation Li-ion batteries.